Cathode ray device



July 7, 1936. R, QRTH 2,047,030

CATHODE RAY DEVICE Filed Nov. 23, 1952 7.9 77 t9 INVENTOR RICHARD T. ORTH ATTORNEY Patented July 7, 1936 UNITED STATES CATHODE RAY DEVICE Richard T. Orth, South Orange, N. L, assignor to Radio Corporation of America, a corporation of Delaware Application November 23, 1932, Serial No. 643,955

9 Claims.

The present invention relates to cathode ray tubes and particularly to cathode ray tubes in which there are a plurality of accelerating anodes one or more of which may consist of silvering on 5 the inside of the bulb.

In the past many difliculties have been experlenced in establishing firm and secure contacts between the lead wire adapted to supply the necessary voltages to inside silver or otherwise coated portions of the bulb when these coated portions serve as anodes or other electrodes. In order to provide a conducting path and to obtain efficient operation, it is necessary to be particularly careful in constructing cathode ray tubes to provide firm contacts between the silvered surface coating the inner conical portion of the tube envelope and the conductors supplying the operating voltages.

In the prior art it has been customary, so far as I am aware, to flatten the end of the lead wire supplying thehigh operating voltages to the conducting layer on the inner wall of the tube and 'then to bend the wire and secure it to a softened portion of the envelope. After this has been done 5 the contact element, as well as the inside of the tube wall, was appropriately silvered. This general form of construction, while extremely simple in nature, has the drawback that the contact provided in this manner or the contact formed by 30' platinizing and silverin'g frequently opens when exposedto the stresses incident to the temperatures of manufacture. 7

It is, therefore, an object of the present invention to improve the method of establishing elec-' ductor and the cathode ray tube conducting wall. Y

' A further object of the invention is to provide a relatively large contact area so that the i0 difficulties of separation of any small elemental section of the contact surface will have no detrimental effect uponthe tube operation.

Further objects and advantages of the invention are, of course, to. provide cathode ray tubes 45 which can be manufactured with a greater degree of assurance of satisfactory operation and'to providean arrangement which will not increase materially the cost of manufacturing and sealing contacts within cathode ray tubes. 50 vMany other objects and advantages will, of course, become apparent and'at once suggest themselves to those skilled in the art to which the invention is directed by reading the following specification and claims in connection with the 55 accompanying drawing, wherein;

welding.

Fig. 1 illustrates diagrammatically a suitable form of contact element prior to assembling in the complete cathode ray tube;

Fig. 2 is a section on the line 2-2 of Fig. 1 to show the conducting disk element assumed as 5 the contact element in the present invention;

Fig. 3 shows a section of the tube wall with the contact element assembled and prior to sealing to the tube wall; and,

Fig. 4 shows a complete cathode ray tube with a contact to supply high voltages to the accelerating and focusing anode thereof.

Reference may now be made to the accompanying drawing and it will be seen that the conducting member I is arranged to supply high voltage to the tungsten lead wire 3 which is secured thereto at the point 5. The tungsten lead wire 3 passes through the glass stem 1 in any desired manner so as to be appropriately sealed thereto, as is well known in the construction of all types of vacuum tubes. In order to provide an efficient means for joining the glass stem I to the wall I5 of the cathode ray tube 2 the glass stem is made in three separate sections 1, 9 and II because of the fact that the tube wall is usually formed by a glass having a high silica content and low coefllcient of thermal expansion.

Around the end I3 of the conductor which protrudes into the cathode ray tube wall I5 there is wrapped, subsequent to platinizing this end of the tungsten conductor, a fine wire I6, which is preferably of platinum. This conductor or fine wire I6 is wrapped over the entire end I3 of the conductor 3 which protrudes beyond the glass stem 1 and is so wrapped as to extend for several 5 turns at least upon the glass stem I. This wire I6 is then platinized in any desired manner.

About the wire I6 surrounding the lead-in conductor 3 there is crimped, or otherwise suitably fastened, for example, by welding, a bent conductor I l which passes through the central opening in an annular disk I9 and is secured therein in any desired manner, for example, by bending and crimping around the disk surface at a point 2 I. Also fastened to the inner side 23 of the contact disk I9 there is a small diameter magnesium wire 25 which has its end portions 21 and 28 suitably secured to the disk surface, for example, by

With this construction now having been assem- J5 bled the entire arrangement may be inserted within an opening 29 provided in the tube wall I5 of the cathode ray tube 2 and the outer portion I2 of the glass stem, formed of the separate parts I,

of the cathode ray tube.

After this operation has been completed the inner surface 39 oil the tube wall 65 is then suitably silvereol as at 33. for example, to provide I the conducting surface to serve as the tube sec ondary anode. The lead-in conductor 23 is ar ranged so that its axis is co-incident with the axis of the metal flasher ring 99, preferably formed of nickel, and the magnesium flash ring 25. The silver film in being deposited coats not only the inner tube wall 3! but also the conductor it wrapped about the end E3 of conductor 3 and also about the lower or inner end of the glass stem portion I.

The cathode ray tube may now be suitably evacuated providing, of course, that suitable fluorescent material has been applied to the inner surface of the end wall 35 and that the mount including the anode, cathode and grid electrodes (shown in general at 31), or any desired number of electrodes, and, where desired, internal deflecting electrodes, have been positioned within the tube envelope. I

After the tube has been suitably evacuated the metal contact plate It is heated, by induction, for

example, so as to cause the magnesium in the form of the flash ring 25 to vaporize. This results in the deposition of most of the magnesium in a metallic form on and between the wire i6 and the silvered coating upon the glass portion 1 where contact is to be established between the silvering of the tube wall and the lead-in conductor 3. At the same time the construction provides a yieldable connection between the inner tube wall 3| and the lead-in conductor 3 so that the difllculties heretofore experienced in the breakage of contacts in the final assembly of the tube are substantially avoided.

The invention has been above explained particularly in connection with cathode ray tubes. It is, however, to be understood that the subject matter is in no sense specifically limited to cathode ray tubes but may be applied, in general, to

any form of tube where it is desired to establish contact'between a lead-in conductor and a surface within a tube, with the same desirable results. Further, it should be understood in connection with this invention that the silvering need not be upon the wall of the cathode ray tube itself but could be upon any similar surface and,

therefore, the invention must be regarded broadly and as covering a satisfactory method of making contact between two materials which cannot be joined by welding or held together by pressure. It should also be noted that in place of silver plating, gold or platinizing or spraying of metallic coatings could be used and still be within the spirit of the invention.

Many modifications and changes may be made in this invention without departing from its spirit and scope and I, therefore wish it to be understood that I do not intend the invention to be limited to the particular form disclosed but may make all such modifications as fall fairly within the spirit and scope of the hereinafter appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is the following: I

1. A lead-in connection for use in an electron tube comprising a lead wire for supplying operating voltages to an electrode of the tube, said lead wire passing through a portion of the tube wall, a conducting member wrapped around the inner demoed end portion of the lead wire so as to form electrical contact with the lead-in conductor and to be upon the tube wall, and a deposited metallic coating upon the wrapped conducting member and a portion of the electron tube to which operating voltages are to be supplied by the connec tion established between the lead wire and the surface.

2. ii lead-in connection for use in an electron tube construction comprising a lead-in conductor sealed through a portion of the tube wall, a conductor coll about a portion of the lead-in conductor and a portion of the inner tube wall, a conducting metallic film coating 2. portion of the inner tube wall and the conducting wrapping so as to establish electrical connection with the lead-in conductor, a support element secured to the lead-in conductor and positioned adjacent the said film, and a vaporizable metallic member secured to the surface of the support element adjacent the tube wall so that, upon vaporization, a metallic deposit of the vaporizable material is produced on said film so as to improve the electrical contact established between the lead-in conductor and the conducting film.

3. A lead-in connection for use in an electron tube comprising a lead-in wire contained within and protruding beyond an insulating member, a wire having small diameter relative to the diameter of the lead wire wrapped around the end portion of the lead wire and a portion of the insulating member, a conducting metallic film coating the lead wire, the wrapping and a portion of the inner wall of the tube envelope so as to place each element in electrical contact with each other, and a vaporized metallic deposit upon the metal film coating upon the wrapped conducting wire for improving the electrical connection established between the lead-in conductor and the tube wall film coating.

4. A lead-in connection for use in combination with a cathode ray tube having a conducting layer forming a part of the inner tube wall and a. stem portion through which operative voltage is supplied comprising a lead-in conductor positioned within the stem to supply operating voltages to the conducting layer, a support element adjacent the inner tube wall, a platinized coating upon the conductor, a conducting wrapping surrounding a portion of the lead-in conductor and a portion of the stem, a volatile material supported upon the support element on the side thereof ajacent the conducting surface so that upon application of heat to the support element the volatile material is 'voltalized and the resulting metallic deposit serves also to establish contact be tween the lead-in conductor and the surface.

5. The method of establishing contacts between lead wires and a metallic surface within an envelope which comprises positioning a conductor element within the envelope, wrapping the end portion of the conductor element and a portion of the tube wall through which the conductor protrudes with a second conductor element to increase the effective area thereof. simultaneously coating the conducting elements and the inner surface of the envelope with a conducting material and vaporizing a metal in the area surrounding the metal coated conductor to form a metallic surface to improve the contact established between the conductor and the metal coating first applied thereto. I

6. In a cathode ray tube the method of establishing firm contacts between lead wires and a 75' metallically coated tube wall which comprises positioning a contact member adjacent the tube wall, electrically connecting the contact and the lead wire, simultaneously coating the tube wall and the contact area with a metallic material, and coating the joint between the contact area and the metallic surface with a metal coaitng different from the tube wall coating.

'I. A lead-in connection for use in an electron tube comprising a wire for supplying operating voltages to an electrode of the tube, said lead wire passing through a portion of the tube wall, a conducting member wrapped around. the inwardly extending end portion of the lead wire and a portion of the inwardly extending portion of the tube wall through which the lead wire passes so as to form electrical contact therewith, and a deposited metalllc coating upon the wrapped conducting member and a portion of the electron tube to which operating voltages are to be supplied between the lead wire and the surface.

8. A lead-in connection for use in an electron tube construction comprising a conductor sealed through a portion of the tube wall, a conducting wrapping about the inner end portion of the lead-in conductor and a portion of the inner tube wall, and an electrically conducting film coating a portion of the inner tube wall and the conducting wrapping so as to establish electrical connection with the lead-in conductor.

9. The method of establishing contacts between lead wires and a metallic surface within an electron tube which comprises positioning a conductor element within the envelope, wrapping inner surface of the envelope with a metallic con- 20 ducting film.

RICHARD T. ORTH. 

